What are the phases of wound healing? Name their time frames
(0. Hemostasis)
1. Inflammation - 0-5 days
2. Proliferation - 4 days to 2-3 weeks
3. Maturation/Remodeling 20 days after injury - up to years
Explain what happens during the Inflammation phase of wound healing
- initially vasoconstriction and platelet plug formation followed by fibrin clot formation (some separate this as hemostasis phase)
- first: neutrophils reach tissue within 6 hours after injury - release enzymes and phagocytize to remove extracellular debris
- 12 hours after injury - monocytes - become macrophages within 24-48 hours - remove necrotic tissue, bacteria, foreign material
Explain what happens during the proliferative phase of wound healing
- angiogenesis (VEGF, PAF)
- granulation tissue formation - fibroblasts synthesizing collagen and formation granulation tissue
- epithelialization - new epithelium first visible 4-5 days after injury
What is the earliest wound contraction is first noticeable
5 to 9 days after injury
Describe the maturation phase of wound healing
Also called remodelling phase
starts 17-20 days after injury
* myofibroblasts has contractile elemants and lead to wound contraction
* remodelling of collagen fiber bundles
How strong is a scar compared to original tissue?
80%
What are the classifications of wounds based on their contamination?
- clean - surgical, atraumatic aseptic
- clean contaminated - surgical with minor break in asepsis
- contaminated - recent wound related to trauma, can be surgical with major breaks in asepsis
- infected or dirty - older wound with obvious signs of infection
How would you classify the contamination of a surgery entering the GI tract?
clean contaminated
how many bacterial organisms per gram does an infected wound contain?
10^5 organism/gram tissue
What are the grades of open fractures?
Grade 1: small break in skin (<1 cm), bone penetrating from the inside out
Grade 2: soft tissue trauma > 1 cm, usually trauma from outside in and wound is continuous with the bone fracture (e.g., bite wound)
Grade 3: extensive soft tissue injury, commonly high degree comminuted trauma
Whe addressing an open fracture, should you push the fractured bone back in place before bandaging?
no, pushing it back in will likely move contamination deeper into the tisse
At what pressure and for how long do you apply a pneumatic blood pressure cuff as tourniquet?
200 mm Hg for up to 1 hour
During what phase of wound healing is a wet-to-dry bandage most appropriate?
debridement phase (part of the inflammatory phase)
What is the timing for delayed primary wound closure?
2-5 days after injury
delayed secondary closure if after 5 days
List the parts needed for negative pressure wound therapy
- contact layer (e.g., polyurethane foam or gauze sponges)
- suction tubing
- adhesive occlusive film
- suction device - usually set at - 125 mm Hg
- collection cannister
What are the potential benefits of negative pressure wound therapy?
- improved neovascularization
- improved granulation tissue formation
- reduction in wound size
List contraindications for negative pressure wound therapy
- bleeding wound or coagulopathies/receiving anticoagulants
- necrotic tissue with eschar
- untreated osteomyelitis
- malignancies
- exposed nerves, vessels, anastomosis or organs
How is HBOT suspected to improve angiogenesis?
creates an oxygen gradient favoring vascularization
How well does triple antibiotic help for Pseudomonas infections?
not well, poor acitvity against it
What properties of honey make it antimicrobial?
- hydrogen peroxide content
- osmolarity
- acidity
How does cats wound healing differ from dogs?
sutured wounds are only half as strong compared to dogs 7 days later
demonstrate significantly less granulation tissue in wounds healing by second intention
